The present invention disclosed herein relates to an amplifier, and more particularly, to a variable gain amplifier.
Variable gain amplifiers are devices that control a gain and amplify an input signal in order to maintain the amplitude of an output signal in a certain range. For example, when analog circuits process analog audio or video signals, the variable gain amplifiers are used to control the amplitude of an input signal in order for an output signal not to be saturated. In a communication system, alternatively, when the output signal of a transmitter is attenuated by a channel in which a great loss occurs and is inputted to a receiver, the variable gain amplifier compensates for attenuation that is caused by the channel.